1. Field of the Invention
The present invention relates to a load beam constituting a part of a suspension of a disk drive, suspension with the load beam, and a manufacturing method for the suspension.
2. Description of the Related Art
Conventionally, a magnetic disk device, such as a hard disk drive (HDD) or magneto-optical drive, comprises a magnetic head. The head flies above a magnetic disk rotating at high speed with a fine space therebetween. Data on the disk is read or written by the head.
An example of a suspension is disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 10-162532 or 9-91909.
In recent years, the head size and flying height (above the disk surface) have been reduced with the development of disk devices with higher recording densities. In order to accurately read and write magnetic disk data, it is important to suppress vibration of a head portion, thereby precisely positioning the head.
As shown in FIG. 10, a disk drive with a suspension generally comprises a magnetic head 1, a suspension 2 supporting the head 1, a block 3 to which the suspension 2 is fixed, etc. The suspension 2 generally comprises a load beam 10 formed of a precise thin-plate spring, a baseplate 11, a flexure 12 formed of a plate spring thinner than the load beam 10, etc. The magnetic head 1 is located on a gimbal portion formed at the distal end of the flexure 12.
A head portion comprising the magnetic head 1 receives vibration from a device for driving the head portion, a motor (not shown) for rotating a disk 13, etc. Thus, the suspension 2 formed of a plate spring, may be deformed so that the magnetic head 1 is dislocated. This results in a read or write error. Thereupon, the damper 14, such as the one shown in FIG. 11, may be used to reduce or remove vibration of the suspension 2. The damper 14 is also referred to as a vibration damping member. The damper 14 comprises a metallic restrainer 15 and viscoelastic member 16 of a viscoelastic material, which are laminated thickness-wise. The damper 14 is affixed to the load beam 10 of the suspension 2.
According to the suspension 2 with the damper 14, the viscoelastic member 16 sandwiched between the vibrating suspension 2 and restrainer 15 is deformed as the suspension 2 vibrates. Molecular friction of the viscoelastic member 16 produces internal resistance, thereby converting vibrational energy into thermal energy. Thus, the vibrational energy directly received by the suspension 2 is greatly reduced, so that a vibration dumping effect can be obtained. FIG. 12A shows vibration characteristics observed before the damper 14 is affixed to the load beam 10. FIG. 12B shows vibration characteristics observed after the damper 14 is affixed to the load beam 10. As shown in FIG. 12B, a damping effect obtained from the damper 14 affixed to the load beam 10 lowers the peak value of a gain in each vibration mode and provides the vibration damping effect.
As shown in FIGS. 3A and 4A, transversely opposite side edge portions 10a of the load beam 10 are bent in order to enhance the rigidity of the load beam 10. In this specification, the bending of the bent side edge portions 10a is referred to as “rib bending”. In order to maintain an appropriate flying height of the magnetic head 1 above the surface of the disk, moreover, a proximal portion 10b of the load beam 10 is slightly bent, as viewed laterally relative to the load beam 10, as shown in FIG. 4A. The proximal portion 10b is located near the block 3 and also functions as a hinge portion for warping the load beam 10 thickness-wise. In this specification, the bending of the proximal portion 10b is referred to as “load bending”. If the damper 14 is affixed to the load beam 10 before this load bending, it may undesirably interfere with a bending tool during the rib or load bending. In actual manufacturing processes, therefore, the damper 14 is affixed to the load beam 10 after the load beam 10 is bent, as shown in FIGS. 9A to 9D.
In order to cause the viscoelastic member 16 to adhere closely to the load beam 10 in affixing the damper 14 to the load beam 10, however, the damper needs to be pressed against the load beam 10 with a predetermined load. In some cases, the load beam 10 may be deformed by a pressing force on the damper 14 that is affixed to the bent load beam. If the load beam 10 is deformed, static properties, such as spring load, and dynamic properties, such as resonance, may vary. Variations of these properties impair the commodity value and working properties of the suspension.
If the damper is dislocated with respect to the load beam when it is affixed to the load beam, moreover, it may adversely affect the properties of the suspension. Conventionally, it is difficult to accurately position the damper, since the damper is affixed to the load beam formed of a flat thin-plate spring that carries no indication of a damper mounting position.
According to the conventional manufacturing processes in which the damper is affixed to the bent load beam, the opposite side edge portions 10a that are bent like ribs hinder the operation for affixing the damper 14. Since one damper 14 is affixed to each load beam 10, furthermore, the affixing operation is time-consuming, that is, work performance is poor.
Conventionally, the viscoelastic member is sometimes caused to project much from the periphery of the damper by the pressing force on the damper that is affixed to the load beam. In such a case, it is troublesome and difficult to thoroughly remove a projecting part of the viscoelastic member. In some cases, the periphery of the viscoelastic member is covered by a resin coating material after the damper is affixed to the load beam. In these cases, the usage of the coating material is too much to reduce the weight of the load beam.